This is a phase II research study will evaluate the effects of RWJ-57504, a new compound under investigation for the treatment of pain and arthritis. RWJ-57504 is similar to other marketed drugs like Naprosyn or Voltaren. Like these other drugs, it works by blocking an enzyme called cyclooxygenase (COX)-2 which can cause pain and swellings. RWJ-57504 may cause less stomach irritation than Naprosyn or Voltaren because, in contrast to these other marketed drugs, it is not expected to block another enzyme called COX-1 which protects the stomach lining. This study will evaluate the effect of RWJ-57504 on COX-1 versus COX-2 by measuring the blood and urinary levels of substances that result from COX-1 and COX-2 activity.